One of the most common mistakes I see companies and in particular professional service firms making is hiring a web developer that creates a web page that looks professional but isn't user or search engine friendly. Many companies hire a designer based on a referral from another business owner who hasn't had much experience with running websites. Many professional service firms seem to favor companies than design using .asp and flash and other languages that are unfriendly for both users and search engines.
These front end languages are out of favor with most web developers and search engine optimization consultants in the know. The first things I usually end up fixing when I am approached by a client is their on page issues such Title tags, image names, url strings and other basics. Many companies end up having the basics screwed up like having static pages that probably do not change dynamically generated. Most companies pages only get update once every six months at most which means they really don't need dynamic pages let alone the ugly url's that go along with them.
Another big mistake companies make when they create web pages is following the usual corporate template that has been used since 1996. The stand website template for corporate sites was created long before Google when people didn't really understand how to do business on the internet. Most companies create pages full of hyperbole and stuff that doesn't mean anything or get to the core of what you are trying to convey to your audience. Total you can have 20 pages like that, or even 100, some companies have thousands but they don't mean anything if they aren't related to the keywords and search strings your potential clients are searching for. You need to answer the questions a potential client wants to know before choosing to work with you and you have to do it in a way that is both user and search engine friendly. That is the every essence of what a good SEO firm or consultant should be able to help you convey.
Here are a few of the other common mistakes I encounter when clients come to me:
1. Over optimizing and keyword loading pages in a way that makes them unreadable to humans.
2. Having pages filled with meaningless hyperbole.
3. Not optimizing pages for what their users are searching for.
4. Not having title tags and meta tags that match the keywords their users are searching for.
5. Not building links to sub pages and only link building for the home page.
6. Having poor into linking structure and navigation
7. Not making it clear what action you want the user to make.
If your firm is making any of the following mistakes then it is important that you contact an SEO consultant to have them fix the problem.